Your cart is currently empty!
M01.02.021 Mastication
The muscles of mastication are essential for jaw movements at the temporomandibular joint (TMJ). These muscles enable chewing, biting, and other movements critical for oral functions. They develop from the first pharyngeal arch and are innervated by the mandibular nerve, a branch of the trigeminal nerve (cranial nerve V).
Overview of Mastication Muscles
There are four primary muscles of mastication:
- Masseter
- Temporalis
- Medial Pterygoid
- Lateral Pterygoid
Note: These muscles are bilateral structures.
Detailed Anatomy of the Muscles
1. Masseter
- Shape and Location: Quadrangular; superficial to the pterygoids and temporalis.
- Attachments:
- Superficial Part: Maxillary process of the zygomatic bone.
- Deep Part: Zygomatic arch of the temporal bone.
- Insertion: Ramus of the mandible.
- Actions:
- Elevates the mandible (closes the mouth).
- Innervation: Mandibular nerve (V3).
| Feature | Details |
|---|---|
| Origin (Superficial) | Maxillary process of zygomatic bone |
| Origin (Deep) | Zygomatic arch of temporal bone |
| Insertion | Ramus of mandible |
| Action | Elevation (closes mouth) |
| Nerve Supply | Mandibular nerve (V3) |
2. Temporalis
- Shape and Location: Fan-shaped; covers the temporal fossa of the skull.
- Attachments:
- Origin: Temporal fossa.
- Insertion: Coronoid process of the mandible.
- Actions:
- Elevates the mandible (closes the mouth).
- Retracts the mandible (moves jaw posteriorly).
- Innervation: Mandibular nerve (V3).
| Feature | Details |
|---|---|
| Origin | Temporal fossa |
| Insertion | Coronoid process of mandible |
| Action | Elevation (closes mouth); Retraction |
| Nerve Supply | Mandibular nerve (V3) |
3. Medial Pterygoid
- Shape and Location: Quadrangular; located inferiorly to the lateral pterygoid.
- Attachments:
- Superficial Head: Maxillary tuberosity and pyramidal process of palatine bone.
- Deep Head: Medial aspect of the lateral pterygoid plate of the sphenoid bone.
- Insertion: Ramus of the mandible near the angle.
- Actions:
- Elevates the mandible (closes the mouth).
- Innervation: Mandibular nerve (V3).
| Feature | Details |
|---|---|
| Origin (Superficial) | Maxillary tuberosity, pyramidal process |
| Origin (Deep) | Medial aspect of lateral pterygoid plate |
| Insertion | Ramus of mandible (near the angle) |
| Action | Elevation (closes mouth) |
| Nerve Supply | Mandibular nerve (V3) |
4. Lateral Pterygoid
- Shape and Location: Triangular; horizontally oriented fibers.
- Attachments:
- Superior Head: Greater wing of the sphenoid.
- Inferior Head: Lateral pterygoid plate of the sphenoid.
- Insertion: Neck of the mandible.
- Actions:
- Bilateral Action: Protracts the mandible and depresses the chin.
- Unilateral Action: Side-to-side movement of the jaw.
- Innervation: Mandibular nerve (V3).
| Feature | Details |
|---|---|
| Origin (Superior) | Greater wing of sphenoid |
| Origin (Inferior) | Lateral pterygoid plate of sphenoid |
| Insertion | Neck of mandible |
| Action (Bilateral) | Protraction, depression of chin |
| Action (Unilateral) | Side-to-side movement |
| Nerve Supply | Mandibular nerve (V3) |
Key Points to Remember
- All muscles of mastication are innervated by the mandibular nerve (V3).
- Their primary functions include elevation, depression, protraction, retraction, and lateral movements of the mandible.
- The masseter and temporalis are primarily involved in jaw elevation.
- The lateral pterygoid is the main muscle responsible for protraction and side-to-side movements.
- The medial pterygoid assists in jaw elevation.
Bibliography
- TeachMeSeries Ltd. (2024). Muscles of Mastication.
- Moore, K. L., & Dalley, A. F. (2020). Clinically Oriented Anatomy.